BBSxx on Big Hit donor

After building some years ago my first ebike (I think i have a topic about it somewhere on this Forum), I bought, in 2016, a Qulbix 76R frame.. but after receiving it, I realized that wasn't the thing I wanted (I'm selling the frame, it's new..) .. since then the project was "on hold". on july i decided to make it, but on another direction.

So I decided to share my new project here.
I don't have many tools and only an Arc welder, And don't have access to Chromoly.. The first part of the frame building i done it in my parents garage during my vacation there. Now for finishing it i have only a balcony.

The happy (or not) donor was a Specialized Big Hit. (Bought used)


After some work on software Linkage I designed the shape and here is the "pre" result, with my "jig" .
I wanted something cool looking on the FR/DH zone..


Here is the project first shape.. at the time I didn't have the motor yet.


When the motor came... it was not the perfect fit and some mods were needed. (now in balcony)


I took it all apart.. and redone the motor part (this time the tubbing is over the motor)


This is the central part of the frame (4.7Kg).. not bad I think, since it's not Chromoly and I have a lot of tubbing...


More updates to come.. but this is a slow project, I have all winter to make it....

Nice project!
But why not put the BBSHD on the original frame? Doesn't that fit or did you just want to build a frame?

SlowCo said:

Nice project!
But why not put the BBSHD on the original frame? Doesn't that fit or did you just want to build a frame?

Click to expand...

It fits on original Big Hit BB, i think the only problem to be solved is the chainguide mount of the frame. But, the frame have no place for battery (most of FR/DH frames doesn't have).

et voilà. 98% finished... it took me almost a year but like I said it was a "not urgent" project.







I have a second set of wheels with DH rims and DH tyres, not fancy color!

Great build!

How does it ride?

Very nice work! I'm quite impressed with how it turned out. Its a very clean and professional looking build.

Very nice work, the gap at the top creates an EOM vibe to this, really like your framework! 8)

Did you replicate the Bighit's geometry or depart from it?
Would it be possible to see some more of inside the battery area?

I think building my own frame will be on the cards for the next project!

Love it !
What`s your battery specs ?

The battery is 58.8v (full charged) 26.4A, not the best capacity but i had those 2400mA cells for free (154 cells)! I am planning to build a smaller pack with better cells (3200mA or higher and 3C discharging current).

I modded a little bit the geometry of the Big Hit frame on the rear suspension (I bought the Linkage software) to move the shock outside the frame, making more space for battery. If it was now I would maybe build it different, with another type of frame, to look even more "OEM". I choosed the Big Hit frame because it has asymmetric dropouts, so I can fit the biggest tyres possible without chain problems.

The Head tube Angle is 67 degrees (can switch to 63 by mounting the rear shock on 2nd position but for my use now the 67 is fine) and the wheel base is a little bit longer (1185mm with 67 degrees head angle and 1200 with 63) due to longer chain stay (445mm). The rims are 47mm wide with 2.3 Crazy Bob tyres. I have 225mm front rotor and 203 on the back. The battery is removable. The all thing is on heavy side... a little bit over 35Kg, I hope that with the smaller pack it goes down to little above 30Kg. (not bad considering that i have no lightweight frame materials.. double crown fork, big rims, big brakes, big rear shock)

The things that i still have to do/adapt:
- Chain guide
- Chain guard
- Swap the fork coil (it as the silver but i already ordered the red one )
- Smaller size battery pack
- PAS switch
- Throttle switch
- Brake cutoff switch
- Covers for "holes" in the frame (where run the cables and future switches inside the frame)
- Try the 42T chainring that i have here

Edit: Photos


Battery pack

Wow that is nice, BBSHD is great off road motor, quiet and fairly efficient so you can ride for hours if you pedal quite a bit.